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Cereb Cortex. 2015 Sep;25(9):2894-906. doi: 10.1093/cercor/bhu086. Epub 2014 May 16.

Spatial Attention and Temporal Expectation Under Timed Uncertainty Predictably Modulate Neuronal Responses in Monkey V1.

Author information

1
Picower Institute for Learning and Memory, MIT, Cambridge, MA 01239, USA Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA 02129, USA.
2
Picower Institute for Learning and Memory, MIT, Cambridge, MA 01239, USA.
3
Department of Brain and Cognitive Sciences, MIT, Cambridge, MA 01239, USA.
4
Picower Institute for Learning and Memory, MIT, Cambridge, MA 01239, USA Max Planck Florida Institute for Neuroscience, Jupiter, FL 33458, USA.
5
Picower Institute for Learning and Memory, MIT, Cambridge, MA 01239, USA Department of Brain and Cognitive Sciences, MIT, Cambridge, MA 01239, USA.

Abstract

The brain uses attention and expectation as flexible devices for optimizing behavioral responses associated with expected but unpredictably timed events. The neural bases of attention and expectation are thought to engage higher cognitive loci; however, their influence at the level of primary visual cortex (V1) remains unknown. Here, we asked whether single-neuron responses in monkey V1 were influenced by an attention task of unpredictable duration. Monkeys covertly attended to a spot that remained unchanged for a fixed period and then abruptly disappeared at variable times, prompting a lever release for reward. We show that monkeys responded progressively faster and performed better as the trial duration increased. Neural responses also followed monkey's task engagement-there was an early, but short duration, response facilitation, followed by a late but sustained increase during the time monkeys expected the attention spot to disappear. This late attentional modulation was significantly and negatively correlated with the reaction time and was well explained by a modified hazard function. Such bimodal, time-dependent changes were, however, absent in a task that did not require explicit attentional engagement. Thus, V1 neurons carry reliable signals of attention and temporal expectation that correlate with predictable influences on monkeys' behavioral responses.

KEYWORDS:

hazard rate; neural responses; reaction time; top-down influences

PMID:
24836689
PMCID:
PMC4635676
DOI:
10.1093/cercor/bhu086
[Indexed for MEDLINE]
Free PMC Article

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